For some 25 centuries, philosophers have attempted to explain and account for our moral experience. They've tried to describe what's worth seeking in human life, along with the moral rules that should guide our behavior and the virtues that constitute human excellence.
Three major categories of philosophical ethics stretch back to ancient Greece and continue into the present. One, focusing on the consequences of actions, holds that pleasure or happiness is our basic goal; here the right thing to do is to maximize pleasure or happiness. The second category emphasizes reason, claiming that duty, rights, and justice are basic. The third category considers what it means to lead a good life, along with the role virtue plays in that life.
All three trends combine to influence the current discussion of moral problems. By becoming familiar with them, we can learn to think more clearly about moral issues. We can defend our decisions or opinions to others who are affected by them. And we can more effectively participate in today's discussions about the morality of public policy issues.